https://support.google.com/chrome/answer/1181035 contains info on how the encryption works.

chrome://terms/ links to https://www.google.com/intl/en/chrome/browser/privacy/ which links to http://www.google.com/policies/privacy/ to define "how we use information we collect." From that page: "We use the information we collect from all of our services to provide, maintain, protect and improve them, to develop new ones, and to protect Google and our users. We also use this information to offer you tailored content – like giving you more relevant search results and ads."

Your full browsing history is a treasure trove of information useful for making Google's core services (search and ads) more effective. They would be stupid not to use it to improve the quality of their services. I challenge your assertion that Chrome is an altruistic endeavor.